Submission #554673

#	Time	Username	Problem	Language	Result	Execution time	Memory
554673		Alma	Traffic (IOI10_traffic)	C++17	100 / 100	986 ms	147384 KiB

traffic

#include <bits/stdc++.h>
#include "traffic.h"
using namespace std;
 
typedef long long int ll;
 
vector<vector<int>> graph;
vector<ll> cost;
vector<bool> visited;
vector<ll> DP;

int arenaCity;

ll traffic (int city) {
    if (DP[city] != -1) return DP[city];
 
    DP[city] = cost[city];
    visited[city] = true;
 
    for (int road: graph[city]) {
        if (!visited[road]) DP[city] += traffic(road);
    }
    return DP[city];
}

void untraffic (int city, int cityMaxDiff) {
    int bestCity = city;
    ll bestDiff = cityMaxDiff, maxCongestion = DP[city];
    // cerr << city << ' ' << cityMaxDiff << '\n';

    for (int road: graph[city]) {
        // if (DP[road] < maxCongestion) continue;
        ll diff = maxCongestion - DP[road];
        // cerr << diff << '\n';
        
        if (diff < bestDiff) {
            bestCity = road;
            bestDiff = diff;
        }
    }

    if (bestCity != city) {
        DP[city] -= DP[bestCity];
        DP[bestCity] = maxCongestion;
        arenaCity = bestCity;
        
        ll congestion = 0;
        for (auto road: graph[bestCity]) {
            congestion = max(congestion, DP[road]);
        }

        untraffic(bestCity, congestion);
    }
}

int LocateCentre(int N, int pp[], int S[], int D[]) {
    graph = vector<vector<int>> (N);
    cost.clear();
    DP.assign(N, -1);
 
    for (int i = 0; i < N-1; i++) {
        graph[S[i]].push_back(D[i]);
        graph[D[i]].push_back(S[i]);
    }
    for (int i = 0; i < N; i++) {
        cost.push_back(pp[i]);
    }
    visited.assign(N, false);
    ll congestion = traffic(0);
    
    congestion = 0;
    for (auto road: graph[0]) {
        // cerr << road << '\n';
        congestion = max(congestion, DP[road]);
    }
    // cerr << congestion << '\n';

    arenaCity = 0;
    untraffic(0, congestion);    
    return arenaCity;
}

// int main() {
//     int N = 5;
//     int pp[5] = {10, 10, 10, 10, 10};
//     int S[4] = {0, 1, 2, 3};
//     int D[4] = {1, 2, 3, 4};
//     cout << LocateCentre(N, pp, S, D) << '\n';

//     for (int i: DP) cout << i << ' ';
//     cout << '\n';
// }

• Subtask 1: 25 / 25
• Subtask 2: 25 / 25
• Subtask 3: 25 / 25
• Subtask 4: 25 / 25